Firefox in ubuntu 22.04

[Linux for blind general discussion]

I am running ubuntu 22.04 with the mate desktop (using a startx file as I 
don't normatlly use a gui desktop so only want it up when I need it).  If 
I try to run firefox from the menu I get no response and no firefox.  If I 
try to run it from a terminal I get the following error:
/user.slice/user-1000.slice/session-22.scope is not a snap cgroup

The session number may vary.

Any one know how to get firefox working in this setup?

Thnks
Tom